A child with a fever can be worrisome for any parent. But contrary to what many believe, a fever doesn’t always need to be treated. One of the most common questions I get asked by parents is when to treat a fever and how. This can be difficult and depends on several factors, including the severity of the fever, the level of discomfort your child is experiencing and your child’s response to certain medicines.

When a fever does need to be treated, some parents will ask me about alternating between acetaminophen (Tylenol) and ibuprofen (Motrin, Advil) as a way to treat their child’s fever. In certain situations—not all—a child may benefit from alternating medicines to reduce their discomfort. In all cases, if you are considering using this method to treat your child’s fever, always consult your doctor first.

While some pediatricians may recommend this, no clinical evidence exists to suggest that this method is more effective than using just one type of medicine to treat a fever. In general, if your child does need a fever reducer, it is best to choose one type, either acetaminophen or ibuprofen. If the fever reducer you choose doesn’t seem to work, consult your doctor.

If your doctor does recommend alternating, it’s important to note that this approach allows you to give medication to your child more frequently (up to every three hours as opposed to every six hours with a single type of medicine). This creates an easy opportunity for overdose that parents need to take steps to prevent. Though it’s rare, when I do suggest this approach for alternating, I always stress that parents write down on a piece of paper the dosage of each medicine used and the exact time it was given in order to avoid an accidental overdose. This is very important because when you have a sick child who is up at 3 a.m. and you’re exhausted, it can be very easy to lose track of time and proper dosing intervals.

So when might this method be beneficial, and when would it not? Consider the following scenario:

A parent gave his child ibuprofen (Motrin) at 10 p.m., before putting him to bed, to treat a fever. At midnight, the father went to check on his child. The fever was still there—101° F—but the child was sleeping comfortably. The father called me asking what he should do. Because the child was sleeping soundly, my advice was to not give him additional medication. Let him rest. His next dose of ibuprofen (Motrin) could be given at 4 a.m., if he needs it.

Seems straightforward enough. So when might it be beneficial to alternate medicines? Consider this example:

Recently, a mother brought her child into my office with a fever of 105° F, who was having a febrile seizure. It can be challenging to examine children under these circumstances to determine the cause of the fever and if more urgent medical attention might be required. First I gave the child Motrin, but after more than an hour, his temperature hadn’t changed. Rather than wait another five hours to give him a second dose of ibuprofen (Motrin), I gave him acetaminophen (Tylenol) in hopes of controlling his symptoms. Within two hours, the child’s fever was down to 100.7° F. He was finally lucid and I was able to examine him in the office. After another hour, he was able to go home. In this instance, alternating this child’s dosing might have been a key element to controlling his specific symptoms enough so that he did not require a visit to the ER.

This method of treatment, however, is not a typical practice and is often not recommended by pediatricians because of the risk of an accidental overdose. But as you can see in the second example, there are very specific circumstances in which it might be useful.

After speaking with your pediatrician, if you decide that alternating medicines is the best method to treat your child’s fever, it’s absolutely vital that you maintain six hours in between the use of the same medicine, while alternating between medicines every three to four hours. For example, if you give your child acetaminophen (Tylenol) at noon, you can give him ibuprofen (Motrin) at 3 p.m. and then acetaminophen (Tylenol) again at 6 p.m. and ibuprofen (Motrin) again at 9 p.m. Neither medicine should be used for more than 24 hours without consulting a physician.

No matter how you and your doctor decide to approach treating your child’s fever, keep in mind these other important safety tips:

Most physicians recommend only treating a fever with medicines if the fever is above 102° F.

Talk to your doctor before giving a pain reliever or fever reducer containing ibuprofen if your baby is younger than 6 months.

Talk to your doctor before giving acetaminophen to a child younger than 2 years to obtain the proper dosing instructions.

Temperature in infants can be most accurately measured using a digital rectal thermometer.

Before giving your child any medicines, make sure you know your child’s weight. Dosing is based on weight, not age.

Make sure to read the package label very carefully for proper dosing.

Acetaminophen is most commonly administered at a dose of 10 mg/kg to 15 mg/kg every four hours, whereas ibuprofen is usually administered at a dose of 10 mg/kg every six hours, so the pattern of alternating these two medicines may not be apparent to some.

Always use the measuring device that comes with the medicine. Do not mix and match dosing devices.

Don’t give aspirin to anyone under 12 years of age unless instructed by your doctor.

Call your doctor if your child’s fever is not responding to treatment or lasts longer than one day.